Arc rotation measurement in a low-power plasma torch

In this work measurements of the are rotation in a low-power plasma torch a re described. The torch which is being developed for diamond synthesis oper ates with Ar/H-2 mixtures at total pressures inside the expansion vessel of less than 5000 Pa and currents up to 14 A. A specific four-sectors anode a rrangement was developed to measure the are rotation. An external magnetic field, smaller than 80 G at the electrode region, was available to study it s influence on the are rotation. From the correlation technique applied to the current signals collected by the anode-sector angular rotation frequenc ies in the range 35-50 rad s(-1) were measured.